The present invention relates to data communications equipment (DCE) and to computer systems. In particular, this invention relates to the use of data communications equipment to provide secure access to a computer system.
The use of computers in today's world is continually on the increase, from main-frames to personal computers, more and more people are using computer systems. In fact, it is the accessibility of a computer itself, via a modem and the public switched telephone network (PSTN), that allows almost anyone to benefit from the use of a computer. Unfortunately, this accessibility also seems to attract "intruders," i.e., illegitimate users of a computer system. As a result, the security of a computer system, or even a network of computers, as to both the integrity and distribution of the information stored on a computer, is an item of continuing concern to the legitimate users, owners, and operators of computers. In response to this need of providing some type of access security to a computer system a number of alternatives have been proposed.
U.S. Pat. No. 5,003,595, issued to Collins et al. on Mar. 26, 1991, uses the automatic number identification (ANI) of the calling party to determine if the calling party is allowed to access a computer system. In particular, a private branch exchange (PBX) detects and separates, from a calling party's telephone call, the calling party's ANI. The PBX sends the calling party's ANI to an adjunct processor, which is a computer that is designed to work in conjunction with the PBX, for analysis. The adjunct processor compares the calling party's ANI to a list of numbers that includes the automatic number identifications of all authorized users of the respective computer system that the calling party is trying to access. If the calling party's ANI is on the list of numbers for the respective computer system, then the call is completed. However, if the calling party's ANI is not on the list of numbers, the call is not answered.
U.S,. Pat. No. 4,876,717, issued to Barron et al. on Oct. 24, 1989, also uses an adjunct processor in association with a PBX for providing secure access to a computer system. In this system, an incoming telephone call is answered and the calling party is prompted, via a voice recording, to enter identifying information, which can either be a voiceprint or a touch-tone signal. If there is a match between the identifying information, entered by the calling party, and respective identification information in the adjunct processor, the telephone call is terminated and the adjunct processor calls back the original calling party to establish a data call between the original calling party and the desired computer system. However, if the adjunct processor can not match the stored identification information with the calling party's identifying information, the telephone call is just terminated with no further action being taken by the adjunct processor.
U.S. Pat. No. 4,520,233, issued to Smith on May 28, 1985 uses a separate box called a "secure access unit," which is connected between the called party's modem, e.g., the computer's modem, and the central office. In particular, the secure access unit answers any incoming telephone call and waits for the additional entry of touch-tone information representing a 5 digit security code. If this security code is not detected within a particular time-frame, e.g., 23 seconds, the incoming telephone call is disconnected. However, if the secure access unit detects the correct security code, then the called party's modem is connected to the calling party's telephone call to allow access to the respective computer system.
The above-mentioned prior art, while providing secure arrangements to access computers, are not the complete answers to the problem. For example, the Collins et al. and Baton et al. patents both require the use of an adjunct processor, in conjunction with a PBX, a solution that appeals more to a medium, or a large, size business customer. On the other hand, the Smith patent, albeit providing a service more in tune to the small business and residential markets, requires that the incoming telephone call be answered in order to enter the appropriate security code and that the called party purchase an additional piece of equipment.